Miss USA Crystle Stewart, 26, of Texas celebrates after casting her vote at Quail Valley Middle School on Tuesday, Nov. 4, 2008, in Missouri City. According to Rock the Vote, there were 44 million eligible young voters in 2008.

Political dysfunction in the nation’s capital is leaving its mark on the youngest generation of voting-age US citizens: Only 1 in 4 Millennials think the US is headed in the right direction.

Among Americans age 18 to 29, 48 percent think their vote will not make a real difference, up dramatically from 29 percent in 2012, according to a poll released Tuesday by the Institute of Politics at Harvard University in Cambridge, Mass.

This cynical attitude portends lower participation in future voting and civic participation for Millennials, who showed up in record numbers in the 2008 election, said Trey Grayson, director of the Institute of Politics.

“With the hard choices that all of us need to make, it is more important than ever that young Americans are able to connect with and trust elected officials and public institutions,” Mr. Grayson said in a statement. “To ensure progress, our leaders in government need to set a positive tone and work together to show young people that Washington can again deliver results.”

Millennials have become increasingly skeptical of the political process, said Alex Wirth, a Harvard sophomore and one of the project’s student committee members.

“Even young people who are politically active believe their votes won’t make a difference,” Mr. Wirth said in a conference call Tuesday.

Trust that the nation’s major institutions – the US Supreme Court, president, Congress, Wall Street, and even the media – will “do the right thing” all or most of the time has declined among Millennials since 2010.

“Nearly half of all Americans under 30 believe that the politics of today are not able to meet the challenges our country is facing. We have been warned,” said John Della Volpe, polling director of the Harvard Institute of Politics, in a statement.

Along with the growing distrust of politicians and government institutions, Mr. Della Volpe said the survey also illustrates a deepening partisanship among young Americans: 85 percent of Millennial Democrats approve of the president compared with 11 percent of Millennial Republicans, the largest job approval divide the poll has seen for President Obama. One year ago, the divide was 63 percentage points.

“At no time since President Obama was elected in 2008 have we reported less trust, more cynicism and more partisanship among our nation’s youngest voters,” Della Volpe wrote in the report’s conclusion. “Young voters, like older Americans, are becoming more partisan by the day.”

The expanding partisan gap can be seen in Millennials’ views on top issues including immigration, government spending, and gun control.

Immigration: In 2010, 23 percent of Democrats and 20 percent of Republicans agreed that recent immigration into the US had “done more good than harm.” And that divide increased to an 11-point difference in 2013 when 31 percent of Democrats and only 20 percent of Republicans agreed. Overall, 44 percent of Millennials believe that those currently in the country illegally should be afforded a path to citizenship as long as they do not have criminal records, have paid taxes, learn English, and pay a fine.

Government spending: The difference between Democrats and Republicans who agree that “government spending is an effective way to increase growth” was 17 percentage points in 2010 (35 percent of Democrats versus 18 percent of Republicans). In 2013, the divide increased to 24 points with 36 percent of Democrats agreeing compared with 12 percent of Republicans. The economy remains the top concern for Millennials, and “creating jobs and lowering the unemployment rate” beat other issues – including education, gun violence, and immigration – in 75 percent of comparisons.

Gun control: The percentage of Democrats who believe that our gun laws should be more strict increased by 8 points since 2011 (from 61 percent to 69 percent), and the portion of Republicans who believe the same decreased by 7 points (from 27 percent to 20 percent). Overall, 49 percent of Millennials support stricter gun laws, 35 percent say no change is needed, and 15 percent say laws should be less strict.

The polling data is based on surveys of 3,103 US citizens, ages 18 to 29, and was conducted by research company GfK between March 20 and April 8. According to the survey, 37 percent consider themselves Democrats, 25 percent Republicans, and 37 percent independents.